Closes #2920 add copilot instructions

.Rbuildignore

@@ -26,6 +26,8 @@
 ^admiral.*\.tar\.gz$
 ^admiral.*\.tgz$
 ^\.lycheeignore$
+^AGENTS\.md$
+^tests/testthat/AGENTS\.md$
 ^staged_dependencies.yaml$
 ^inst/dev_dependencies.R$
 ^vignettes/articles$

.github/copilot-instructions.md

@@ -0,0 +1,40 @@
+# GitHub Copilot Instructions - admiral Development
+
+**Auto-generated:** 2026-02-23 19:17:54
+**Optimized for:** GitHub Copilot code completion
+**Complete guidelines:** See `AGENTS.md` files for full context
+
+⚠️ **DO NOT EDIT MANUALLY** - Run `source('.github/scripts/sync_admiraldev_copilot.R')` to update
+
+## Admiral Code Completion Patterns
+
+### Function Names (verb_object_detail)
+- `derive_var_base()` - Single variable derivation
+- `derive_vars_merged()` - Multiple variables from merge
+- `derive_param_tte()` - Parameter derivation
+- `compute_age_years()` - Vector computation
+- `assert_data_frame()` - Input validation
+
+### Argument Patterns
+Standard admiral function signature:
+- `dataset` - Always first argument
+- `by_vars = exprs(...)` - Grouping variables
+- `order = exprs(...)` - Sorting expressions
+- `new_var = VAR` - New variable (symbol)
+- `filter = PARAM == "VALUE"` - Filtering expression
+
+### Common Expressions
+- `subject_keys = exprs(STUDYID, USUBJID)`
+- `by_vars = exprs(USUBJID, PARAMCD)`
+- `order = exprs(AVISITN, desc(ADY))`
+- `filter = PARAMCD == "TEMP"`
+
+### Test Patterns
+- Use `tribble()` for test data
+- `expect_true("DERIVED" %in% names(result))`
+- `expect_false(is.grouped_df(result))`
+- `expect_error(..., "Required variable.*missing")`
+
+---
+
+*This file is optimized for GitHub Copilot code completion. For complete admiral development guidelines, see `AGENTS.md` and `tests/testthat/AGENTS.md`.*

.github/workflows/sync-admiralci-agents.yml

@@ -0,0 +1,22 @@
+name: Create the AGENTS.md
+
+on:
+  push:
+    branches:
+      - 2920-add-copilot-instructions
+    paths:
+      - '.github/workflows/sync-admiralci-agents.yml'
+  workflow_dispatch:
+  schedule:
+    - cron: '0 8 6 * *'
+
+jobs:
+  create-agents-md:
+    permissions:
+      contents: write
+      pull-requests: write
+    uses: pharmaverse/admiralci/.github/workflows/create-agents-md.yml@231-add-workflow-to-create-ai-agentmd-files
+    with:
+      package_name: admiral
+      target_branch: 2920-add-copilot-instructions
+      admiralci_ref: 231-add-workflow-to-create-ai-agentmd-files